摘要
在?80mm×3000mm气流床和?40mm×200mm流化床中进行了O_2、H_2O、H_2O+O_2气氛下800℃胜利褐煤气化实验,同时在流化床中进行了O_2、H_2O、H_2O+O_2气氛下半焦原位气化实验和H_2O气氛下半焦完全气化实验。比较了2种反应器中氧化反应与水蒸气气化反应协同作用的大小(强弱);结合实验条件利用缩核模型分别推导了2种反应器中协同作用影响下水蒸气气化反应速率方程;同时,从传质(扩散)速率、动力学、半焦-挥发分相互作用3方面探讨了2种反应器中协同作用存在显著差异的原因。结果发现,气流床中H_2O+O_2气氛下褐煤转化率明显大于H_2O和O_2单独气氛下褐煤转化率之和,其差值稳定在2.11%～4.01%,而在流化床中差值仅为0～0.75%,相对流化床,气流床中协同作用更明显。这是由于,在流化床中水蒸气向炭粒表面扩散的传质速率约为气流床的11%～25%,水蒸气气化过程受气膜扩散控制,炭粒表面水蒸气全部参与气化反应,炭粒表面无"多余"水分子,氧气开孔/扩孔作用提供的活性位"闲置",而气流床中气化反应为速控步,炭粒表面有"富裕"水分子,可充分利用氧气开孔/扩孔作用提供的活性位,促进作用显著;挥发分-半焦相互作用不是流化床反应器中协同作用不显著的原因。
Shengli brown coal was gasified at 800℃ under O2, H2 O, H2 O+O2 atmospheres comparatively by using a entrained-flow reactor with ?80× 3000 mm and a fluidized-bed reactor with ?40 mm×200 mm.Besides, in the fluidized-bed reactor, situ char gasification experiments under O2, H2 O, H2 O + O2 atmospheres and complete gasification experiments(coal conversion is close to 100%) under H2 O atmospheres were carried out to investigate the promoting effect of oxidation reaction on steam gasification reaction in different reactors. The rate equations of steam gasification reaction in two reactors were deduced based on unreacted shrinking core model. The results showed that the lignite conversion under H2 O+O2 atmospheres was greater than the sum of those under H2 O atmosphere and O2 atmosphere with a difference of 2.11%-4.01% in the entrained-flow reactor. In contrast, only 0-0.75% difference was observed in fluidized-bed reactor. The obtained difference can be explained that in the fluidized-bed reactor the mass transfer rate of steam to the carbon particles surface was 11%-25% of that in entrainedflow reactor and the steam gasification reaction occurred in the membrane diffusion controlled regime.This poor mass transfer led to a low steam concentration on carbon particles surface and some idle micro-/mesopores created by O2. However, in entrained-flow reactor the steam gasification reaction happened in chemical kinetic controlled regime, and the rich steam can be absorbed by pores(created by O2) on carbon particles surface to promote steam gasification. Moreover, it was verified that the volatile-char interaction was not main reason of the weak promotion of oxidation reaction to steam gasification reaction in the fluidized-bed reactor.
作者
程相龙
郭晋菊
王永刚
申恬
孙加亮
张海永
CHENG Xianglong;GUO Jinju;WANG Yonggang;SHEN Tian;SUN Jialiang;ZHANG Haiyong(School of Materials and Chemical Engineering, Henan University of Urban Construction, Pingdingshan 467036, Henan,China;Henan Province Engineering Laboratory of Coal-Salt Resources Efficient Utilization, Henan University of Urban Construction,Pingdingshan 467036,Henan,China;School of Chemical and Environmental Engineering,China University of Mining and Technology (Beijing),Beijing 100083,China)
出处
《化工进展》
EI
CAS
CSCD
北大核心
2019年第5期2179-2188,共10页
Chemical Industry and Engineering Progress
基金
国家自然科学基金(21506251)
"十二五"国家科技支撑计划重点项目(2012BAA04B02)
河南城建学院高级人才科研启动基金(2017015Q)
煤盐资源高效利用河南省工程实验室(河南城建学院)开放基金
关键词
水蒸气气化
气流床
流化床
协同作用
气化速率
挥发分-半焦相互作用
steam gasification
entrained-flow reactor
fluidized-bed
the promotion effect
gasification rate
volatile-char interaction
